Relay construction



Oct. 4, 1960 T. E. GARDNER RELAY CONSTRUCTION Filed May 27, 1954' 3Sheets-Sheet l INVENTOR THOMAS E. GA RDA/ER AGENTS Oct. 4, 1960 T. E.GARDNER 2,955,240

RELAY CONSTRUCTION Filed May 27, 1954 I5 Sheets-Sheet 2 INVENTOR. THOMASE. GARDNER 1960 T. E. GARDNER RELAY cowsmucwxou 3 Sheets-Sheet 3 FiledMay 27, 1954 AU TO.

INVENTOR THOMAS E. GARDENER AGENTS United States Patent Ofiice 2,955,240Patented Oct. 4, 1960 The present invention relates to a relay and moreparticularly to an improved electro-magnetic relay having a high degreeof control and adjustability to provide a high drop-out of the relay atany selected value within its entire rated range of operation.

A present day relay possesses a minimum and maximum pickup or contactmaking value which provides the relay with a rated range of operation.This rated range of operation is generally determined by the number ofturns of wire in the coil assembly of the relay as well as the size ofwire employed to make up the coil.

However, such relays possess an undesirable operational characteristicthat has limited their use or necessitated the use of additionalequipment to compensate for or oifset such a characteristic. Thisobjectionable feature is due to the fact that such prior relays willdrop out or break contact only at a value just below the rated minimumpick-up value. By way of example, a relay having a rated range ofoperation of 4 to 16 amperes is employed extensively in the powertransmission field as a safety device. In such a relay, it will normallydrop out at about 3.5 amperes. In the normal use of this relay, thesystem conditions often require that the relay be adjusted to pick-up ormake contact at an intermediate value i.e. amperes. When this operationis necessary, the usefulness of the relay is materially lessened sincethe relay will still drop-out or break contact at a point just below theminimum pick-up value i.e. 3.5 amperes, of the relay. This low drop-outfeature when an operational setting other than the minimum value isemployed often results in a false indication of power line conditionswhich could be harmful thereto as well as being generally economicallyand operationally undesirable.

This objectional inherent low drop-out characteristic of prior relayshas been found to be primarily due to the fact that the distance or theair gap spacing between the fixed pole and the movable pole or armatureis always the same when the armature is picked-up to close the circuit,regardless of the pick-up setting of the relay. Thus, the relay then canonly drop-out at the drop-out value of just less than the minimumpick-up setting since no compensation has been made for the adjustmentof the increased pick-up value above the minimum setting.

It has been found that the high drop-out of a relay is possible at anyvalue throughout the entire rated range of operations of any given relayby providing a relay with an adjustable or variable air gap between thefixed and movable poles of the relay to coordinate with the adjustedpick-up value above the minimum value. By providing the relay with'theadjustable gap, the difference between the pick-up value and thedrop-out value will remain the same throughout the entire rated range ofoperation of the relay. Thus, such a relay made in accordance with thepresent invention and having, for ex ample, a minimum pick-up value of 4amperes and a drop-out value of 3.5 amps, will have a drop-out value of9.5 amps when the operating pick-up value is adjusted to 10 amps.

It is therefore a principal object of the present invention to provide arelay having a fine degree of adjustability of calibration throughoutits rated range of operation.

Another object of the present invention is to provide a relay having ahigh drop-out value at any selected pickup value within the entire ratedrange of operation of the relay.

A further object of the present invention is to provide a relay havingan adjustable air gap between the fixed and movable poles of the relay.

Yet another object of the present invention is to provide a relay inwhich the diiferential between the rated minimum pickup value and thedrop-out value will be the same throughout the rated range of operationfor the relay.

Still another object of the present invention is to provide a relay ofthe plunger-type which will possess a high drop-out value throughout therated range of operation.

Yet a still further object of the present invention is the provision ofa relay having a time delay action to prevent instantaneous tripping.

An additional object of the present invention is the provision of arelay having adjustability both with respect to pick-up and drop-outcurrent values.

Another object of the present invention is the provision of a relayrequiring but a simple adjustment to select the desired pick-up valueand simultaneously set the air gap spacing to provide a high drop-outwith respect to the selected pick-up value.

A still further object of the present invention is the provision of arelay that is a low-burden instrument having universal use in a widerange of use with either current or voltage sources.

Yet another object of the present invention is the provision of a relaythat is of simple construction and requires very little time and effortto adapt to existing relays.

Yet another object of the present invention is the provision of a relaythat will positively seal-in when contact is made and will in additiontend to eliminate chattering.

Other and additional objects of the present invention will becomeapparent from the following description taken in conjunction with theannexed drawings.

Broadly stated, =an electro-magnetic relay made in accordance with thepresent invention comprises magnetic circuit means, having a minimum andmaximum pick-up value, a fixed pole member constituting a portion of themagnetic circuit means, a movable pole member constituting a portion ofthe magnetic circuit means, said pole members being opposed to andspaced from one another forming an air-gap spacing therebetween, andmeans to adjust the air gap between the pole members when other than theminimum pick-up value is employed.

To the accomplishment of the foregoing and related ends, the presentinvention then consists of the means hereinafter fully described andparticularly pointed out in the claim, the annexed drawings and thefollowing description setting forth in detail certain means in thecarrying out of the invention, such disclosed means illustrating,however, but several of the various ways in which the principle of theinvention may be employed.

The present invention is illustrated, by way of example, in theaccompanying drawings in which:

Figure 1 is a front elevation of one form of a relay made inaccordance-with the present invention;

Figure 2 is a side elevation of the relay: shown in Fig. 1;

Figure 3 is a topplan of the relay shown in Fig. 1;

Figure 4 is a cross sectional view of the relay shown in Fig. 1illustrating the detailsof the coil assembly and the pole construction;

Figure 5 is a front elevation partly in section of a second form of theinvention.

Figure 6 is a side elevation of the relay shown in Fig.

Figure 7 is an enlarged perspective view of an attachment plate to bemounted on the relay as shown in Fig. 5.

Figure 8 is a fragmentary front elevation of a third form of a relaymade in accordance with the present invention by which the adjustabilityof the air cap gap can be achieved;

Figure 9 is a fragmentary schematic wiring diagram illustrating a methodof providing a tight sealing-in of the contact of the relay when usedwith a tripping circuit.

Figure 10 is an exploded fragmentary view of the fixed pole illustratingthe slugging of its end to eliminate chattering.

Figure 11 is a schematic wiring diagram illustrating one particular useof a relay made in accordance with the present invention.

Referring now to the drawings and with particular reference to Figs.l-4, an illustrative and preferred form of a plunger-typeelectro-magnetic relay made in accordance with the present inventiongenerally designated by reference number 10 is shown. It is to beunderstood that while the present invention will be illustratedthroughout with reference to plunger-type relays, this is not to beconstrued that the invention only has utility with respect to this type.To the contrary, the present invention can be readily employed withother types of electrd-magnetic relays such as, for example, the clappertype.

The relay 10 comprises a magnetic circuit 11 of generally conventionaldesign and having a coil assembly 12 positional within a metal frame 13which functions as the flux return path. The coil assembly 12 and theframe 13 are each provided with an aligned central opening extendingaxially therethrough to receive a normally fixed pole member 14 in oneend thereof and a movable pole member or armature 15 at the opposite endthereof. This construction results in the formation of an air gap 16between the two pole members 14 and 15 within the coil assembly 12.

The normally fixed pole member 14 is threadably secured to the frame 13and while it is adjustable, it usually will remain in its originallyfixed position. It is preferred that in this particular form of theinvention that means he provided to prevent an accidental movement ofthe pole member 14 from its originally fixed position. This may beaccomplished, as illustrated, by providing the top portion of the frame12 with a split portion 18 extending from its outer edge inwardly alongits top surface to the opening into which the fixed pole member 14 isthreaded. A clamping bar member 19 having its ends turned downwardlyresulting in a generally U-shaped configuration is detachably mounted tothe top portion of the frame 13 over the split 18. The clamping member19 is longer than the width of the frame 12 and has a threaded openingextending through one of its down-turned ends into which a set screw 20is threadably positioned. This construction results in one of thedown-turned ends of the clamping member 19 engaging one side of theleading edge of the top portion of the frame 13 while the set screw 20is adjusted to rest against the opposite edge of the frame 12. Thus atightening on the screw 20 vw'll force a drawing together or a pinchingof the split portio'n 18 and will positively lock the fixed pole members14 to the frame 13 into tight engagement therewith at its desiredposition.

In this form of the invention, an outer metal frame 21 within which themagnetic circuit 11 is centrally positioned in spaced relation theretois necessary. While it has not been positively ascertained, it isbelieved that the outer frame 21 functions in some way in assisting themain magnetic circuit 11 when energized. The basis for this belief isthe fact that a liner control of the relay is possible as well asresulting in a tighter sealing-in of the contacts when the relay 10 isenergized. The primary purpose of the outer frame 21 however is toprovide a mounting by which the means for varying the air gap can besecured.

The fixed and movable pole members 14 and 15 and the top and bottomportions of the outer frame 21 are each provided with an alined openingresulting in a passage extending completely through the entire magneticcircuit 11 and the outer frame 21 axially thereto. A threaded mountingshaft or stud 22 extends completely through and beyond this resultingpassage and functions to connect the magnetic circuit 11 to the outerframe 21 and to additionally provide a guideway for the movement of thearmature 15. A lock nut 23 is secured to the shaft 22 on top of theouter frame 21 to connect them together in locked position. Similarly,the opposite end of the shaft 22 is provided with an adjustable stopplate 24 in the form of a disk or the like to act as a stop against thedownward movement of the armature 15. The stop plate 24 may be held inplace by means of a lock nut 25.

An insulated contact plate 26 is secured to the bottom face of the outerframe 21 by screws or the like. The contact plate '26 is made from anon-conducting, nonmetallic material and is provided with a plurality ofcontact assemblies 27 secured to its bottom surface thereon. The contactassemblies 27 each comprises a metal strip 28 secured to the bottomsurface or face of the contact plate 26 by means of a screw 29, acontact point 30 positioned on and adjacent the inner end of the strip28 and a binding post member 31 secured to the opposite end of the strip28. This assembly functions as one contact making point for the relaycircuit when the relay 10 is energized.

A metal contact plate 32 is fixedly secured by any suitable means to theouter free end of the movable pole member or armature 15 and ispositioned below the insulated contact plate 26. Thus upon anenergization of the magnetic circuit the movable core member 15 ispicked-up or pulled in causing the metal contact plate 32 to engage thecontact points 30 carried by the insulated plate 26 to close theactuating circuit of the relay.

In this form of the invention illustrated in Figs. 1-4, the air gap isvaried to provide the high drop-out characteristics by moving the coilassembly 11 up or down with respect to the outer frame 21 and themovable core number 15. To accomplish this, a sliding bar 33 ofnon-conducting metal, such as, for example, brass, is permanentlysecured to one side of the frame 13 between it and the outer frame 21.The bar 33 is provided with a threaded passageway extending completelytherethrough, through which an adjusting screw rod 34 is positioned. Thescrew rod 34 has one end resting against the inner face of the bottomportion of the outer frame 21 with the other end resting against theinner face of the opposite top portion of the outer frame 21. Thisconstruction results in a raising and lowering of the magnetic circuit11 upon an actuation of the screw rod 34. To facilitate the actuation ofthe screw rod 34, the face of the outer frame 21 immediately adjacentthe actuating end of rod 34 is provided with a small opening to permitthe passage of a screwdriver therethrough to engage the actuating headof the rod.

To insure the locking of the magnetic circuit 11 in place at all times,the outer frame 21 is provided with a guideway slot 35 along its sideimmediately adjacent the bar 33. The bar 33 possesses a threaded openingin alignment with the slot 35. A locking screw 36 extends through theslot 35 and into the threaded opening of the bar 33 where, upon atightening of the screw 36, the magnetic circuit 11 will be tightlysecured to the outer frame 21 against any movement therewith.

It will be found advantageous in the many uses of the relay 10 toprovide indicating or calibrated means to show the degree of adjustmentor the pick-up setting at which the relay is operating. This may be doneby providing one of elongated free face of the bar 33 with channelguideway means 37 into which an indicating plate 38 is slidablypositioned. The plate 38 will contain various calibrated settings toindicate, by comparison with a fixed point carried by the outer frame 21immediately adjacent the indicating plate 38, the operating conditionsof the relay 10.

In the operation of prior relays, the adjusting of such relays to permitit to operate at a higher pick-up value than its minimum rated value hasbeen accomplished merely by lowering the stop plate thus causing thearmature to be lowered. This lowering increases the distance between thearmature and the fixed pole of the magnetic circuit thus requiring-agreater energization to pick-up the armature. In the form of theinvention shown in Figs. 14, it is possible to simultaneously adjust therelay to pick up at a desired setting or value other than the minimumsetting and at the same time vary the air gap between the fixed andmovable poles of the relay so that the drop-out differential will be thesame as that existing when the relay is operating at its minimumsetting.

By way of illustrating a relay made in accordance with this form of theinvention and having a ampere minimum setting and a maximum setting of40 amperes will be described in use, for example, in a powertransmission system. Conditions in the power system often require thatthe pick-up value of the relay be well above its minimum pick-up valueof 10 amperes i.e. 30 amperes. To set the relay to pick up at 30 amperesall that is necessary is to first loosen the locking screw 36 and thento adjust the magnetic circuit by the use of a screwdriver or screw rod34 until the indicia on the indicating plate 38 corresponding to 30amperes is aligned with a fixed point or setting on the outer frame 21.The locking screw 36 is then tightened to lock the adjusted magneticcircuit in its desired value. This adjustment thus assures that therelay will pick up at 30 amperes and will drop out at about 29.5 amperessince the air gap distance has been varied from what it was for theminimum setting.

Referring now to Figs. 5-7, a second form of a relay made in accordancewith the present invention is shown. In this modification, the air gapis varied by limiting the distance the armature and its contact platecan travel during the pick-up occasioned by the energization of therelay. In this description like numerals will be employed for partscorresponding to like parts in the form of the invention shown in Figs.1-4.

The relay 40 has basically the same magnetic circuit 11 as the preferredform described hereinbefore and comprises a coil 12 mounted within aframe 13 and is provided with fixed and movable pole members 14 and 15.In this form of the invention, no outer frame such as outer frame 21shown in the preferred form is required thus it is not necessary toimpart a split portion to the frame 13 to lock the fixed pole member 14in place. In this form of the invention, the fixed pole member 14 may belocked in place by a lock nut 41. Similarly the mounting shaft 22 isheld in place by means of a nut 43a resting against the top free face ofthe fixed pole member 14.

Similarly, the insulated contact carrying plate 26 and its associatedparts hereinbefore described is identical in its basic constructionexcept that its association and mounting with respect to the relay isradically different as will be described more fully hereinafter. Thecontact plate 32 likewise is' of the same structure except partsassociated therewith may be, if desired, modified in the manner morefully described hereinafter.

The insulated contact plate 26 is normally fixed directly to theunder-face of the bottom portion of the frame 13. However, in this formof the invention, it will be necessary to have the insulated contactplate 26 and its associated parts movable vertically with andindependently from the armature and capable of being locked in anyposition.

This vertical movability of the insulated contact plate 32. can beaccomplished by means of a connecting plate 43 which comprises a baseportion 44 and an elongated upright portion 45 positioned to one end ofsaid base at right angles thereto. The base portion 44 is provided withseveral openings 46 by which the connecting plate 43 may be secured tothe top surface of the contact plate 26 by means of screws 47 in fixedrelation thereto.

The upright portion 45 is provided with an elongated guideway slot 48 bywhich the connecting plate may be secured to and in slidable relationwith a mounting frame 49 that is normally carried by the frame 12 of therelay. This association is to permit the upright portion 46 of the frame44 to be secured to the mounting arm or frame 49 by means of a nut andbolt arrangement 50 passing through the elongated slot 48 and throughopenings of the frame 49. This construction makes it possible to connectthe insulated plate 26 to the frame 12 by means of con necting plate 43for independent vertical movement.

It has been found desirable in many instances, particularly in the powertransmission field, to have a time delay action on the relay to preventinstantaneous pickup. To provide this time delay, a dash pot assembly 51may be substituted for the stop plate 24 employed in the form of theinvention shown in Figs. 1 4. The dash pot assembly comprised acylindrical or piston plate at its free end normally resting on thesurface of the oil in the tank 53. The opposite end of the plunger 54 issecured to the contact plate 32 or armature 15 by any suitable means andis movable therewith. When the armature 15 is picked-up upon anenergization of the relay 40, the surface tension of the oil in the tank53 will tend to slow down the upward movements of the armature 15 thusgiving a time delay action before the circuit is closed. It is to beunderstood that if a time delay action is desired for the form of theinvention shown in Figs. 14, the dash pot assembly 51 may be substitutedfor the stop plate 24 shown therein. Alternately, if desired, it is tobe understood that a similar substitution of the stop plate 24 may bemade for the dash pot assembly 51 in the form of the invention justdescribed.

In the operation of this form of the invention to provide the highdrop-out feature when the relay is to be operated above its minimumpick-up value, the dash pot assembly 51 is lowered on the mounting shaft22 causing the armature or movable pole member 15 and the contact plate32 to drop down therewith. This operation is normal in adjusting presentday relays. When the adjustment of the armature 15 has been made toimpart the desired pick-up value to the relay, the screw 50 is nextloosened permitting the connecting plate 43 secured to the insulatedcontactplate 32 to be lowered. After the insulated plate 32 has beenlowered a distance suflicient to achieve the same differential thatexists between the rated minimum pick-up value and the drop-out value,screw 50 is tightened to lock the insulated plate 32 in its newposition. In the operation of the relay 40, it will be obvious that thelowering of the insulated plate 32 will shorten the distance that thearmature 15 can travel during its pick-up operation upon theenergization of the relay 40 thus lengthening the air gap distancebetween the armature 15 and the fixed pole member 14 when the contactsare in engagement. This construction results in the relay dropping outat a high value which is just below the selected pick-up value.

Referring now to Fig. 8 wherein still another construction is shown infragmentary form by which the adjustability of the air gap between thefixed and movable pole members may be accomplished. In this illustrativeform of the invention a conventional relay is used with the onlymodification being made with respect to the movable pole member and itscontact plate normally carried thereby in fixed position.

The movable pole member or armature 15, shown in Fig. 8 will be threadedat its lower end. Similarly, contact plate 56 will be threaded to permitits movement vertically on the armature 15. A lock nut 57 is provided tolock the contact plate 56 at any desired point on the armature 15.Heretofore, the contact plate and armature have been fixed in permanentrelationship to one another permitting no movement with respect to oneanother.

In the operation of the form of the invention shown in Fig. 8, when therelay is to be operated at a pick-up value other than at its minimumsetting, the stop plate 24 is lowered to give the desired pick-up value.The contact piate 56 is then adjusted vertically on the armature 15 to apoint at which the relay will have a high drop-out with respect to theselected pick-up value. The plate 56 is then locked in position. It isbelieved apparent that by the adjustment of the contact plate withrespect to armature 15, the air gap distance will he obviously variedthus giving the desired high drop-out feature.

It will be found desirable in many uses of a relay made in accordancewith the present invention to insure a positive sealing-in of thecontacts, and to prevent or lessen chattering when the relay is used fortripping circuits. Fig. 9 illustrates schematically one manner in whichthis may be accomplished in a tripping action. As shown in Fig. 9, Arepresents a relay made in accordance with the present invention, forexample, the form of the invention shown in Figs. 1-4. B representsseveral turns of wire wrapped around the coil of the relay A with oneend connected to the negative side of a DC. source as at C with theopposite end connected to a dummy contact post D carried by theinsulated contact plate of the relay A. The relay A is connected on oneside to either an A.C. current or AC. voltage source E and on theopposite side to a tripping circuit generally designated by referencenumeral F at the insulated contact plate of the relay A. When the relayA is energized by an AC. power source causing the armature of the relayto pick-up and make contact with the contact plate, the direct currentimposed on the magnetic circuit will result in a flux shifting of theA.C. power source. This action will result in a complete scalingin ofthe contacts of the relay and will eliminate chattering.

Referring now to Fig. 10 wherein a modified form of a fixed pole memberfound desirable to use with a relay made in accordance with presentinvention is shown. This modification will be found useful to eliminatechattering of the relay as well as permitting a more sensitivecalibration of the instrument. In Fig. 10, the fixed pole member 69 isgenerally of conventional design with the exception that the bottom faceof its free end, which will be positioned within the coil assembly, isprovided with a centrally disposed transverse slot 61. A piece of brasswire 62 or other non-conducting wire is then inserted in the slot 61 andwrapped half-way around the lower end of the fixed pole member. Thisconstruction will result in a slugging of the relay iron and willfunction as a flux shifter to reduce chattering of the re.ay.

To illustrate a practical application of a relay made in accordance withthe present invention, reference is now to be had with respect to Fig.11, wherein its use in a capacitor switching control circuit isillustrated schematically. Referring now to the schematic wiringdiagram, A represents the control voltage line from any desired source.The current is supplied by a current transformer in the control voltageline from or by the line in which the capacitors are positioned. Aswitch B is provided for either manual or automatic operation, and inthe following description it will be set in the latter position. A highdrop-out relay C made in accordance with the present invention ispre-set for the heater circuit of a thermal relay D. The thermal relay Dis connected to an auxiliary relay E which is, in turn, connected toactuate a motor F for switching the capacitor.

In the illustrative system, the contacts of the relay C are normallyclosed, the heater circuit of the thermal relay D is inactive or cool.However, when the current reaches a predetermined setting, the contactsof the relay "C will open, resulting in an energization of the heatercircuit of the thermal relay. After a time delay occasioned by theheating up, the thermal relay D will actuate the auxiliary relay E toopen the switch of the motor F. When the current falls below a certainvalue, the contacts of the relay C will pick-up resulting in ade-energization of the heater circuit of the thermal relay D. After atime delay, this action will result in an actuation of the auxiliaryrelay E which will close the switch of the motor F resulting in theswitching of the capacitors.

A red neon la mp G may be present to show that the capacitor motorswitch is closed, while the green neon lamp H is used to show that thecapacitor motor switches 'are open. A toggle switch I may be used toopen or close the motor switch through auxiliary relay E manually whenthe selector switch B is on manual position. A voltage coil also may besubstituted in the high drop-out relay C and supplied by a potential tooperate the circuit as a voltage capacitor switching control.Furthermore, a combination of a current and voltage relay made inaccordance with the present invention could be used for capacitorswitching with current and voltage supervision over the current, or viseversa.

An electro-magnetic relay made in accordance with the present inventionhas a wide field of application and can be employed in any field inwhich present day relays are used. Therefore, the description of the useof the invention with respect to the power transmission field isillustrative in character only. Further, it is to be understood that therelay made in accordance with the present invention may be energized byany power source, such as current or voltage means.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

I claim:

An electro-magnetic relay comprising magnetic circuit means having aminimum and a maximum pick-up value, a fixed pole member constituting aportion of the magnetic circuit means, a movable pole memberconstituting a portion of the magnetic circuit means, said pole membersbeing opposed to and spaced from one another forming an air gaptherebetween, a metal frame around and in vertical alignment with saidmagnetic circuit means, connecting and adjusting means associating saidmagnetic circuit means within said metal frame, for vertical movementtherein independent of said movable pole member to adjust the movablepole member to pick-up at a value above the minimum pick-up value of andsimultaneously adjust the air gap spacing between the pole members tocompensate for the changed pick-up value.

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